I should add:
This problem is less random than it sounds.

At the moment I'm stuck on a single vertex I just want to move slightly. Everytime i touch it I crash instantly. I can move other verticies around though...and If I do some toher things and then come back to this vertex, or possible if I even just zoom out or something, it may well work fine again.

I've deleted construction history, reset Maya's default settings, etc...

Also - it probably wouldn't crash if I changed the view mode to non-textured temporarily...

Makes it very difficult to model indeed...thankfully my Uni deadline is still a few weeks away..